A reeling machine typically has a beam or drum on which is wound a multiplicity of yarns for subsequently forming the warp of woven goods. The individual yarns are pulled from respective supplies on a creel. It is absolutely essential that each yarn be continuous, that is if any yarn breaks while forming the wound warp beam, the winding operation must be stopped so the break can be repaired or a new yarn can be knotted to the broken end before winding can be restarted.
Accordingly it is standard for each yarn to pass over various guides and through a respective eye of a vertical sensor wire. So long as the yarn is taut, the wire is lifted and a switch associated with it is held closed or open. If the yarn breaks, the sensor drops and changes the condition of its switch. If any of the switches moves to an undesired condition, the winding process is immediately shut down.
Normally the yarn supplies are held in the creel in banks, that is arranged in rows and columns. The sensors are similarly organized as the yarns eventually run so close to each other that they could not all be put in a straight line. When one of the yarns breaks a further sensing system can detect which bank the dropped sensor is in, so that the machine operator can find the broken yarn, repair it, and restart the machine. Finding the broken yarn takes some time, increasing the down time when a yarn breaks.
Capacitive sensors are also known which are automatically activated when the winding operation is started. In such a system the exact location of the broken yarn can indeed by ascertained. Nonetheless; even in this system it is a fairly complex job to program the device since it is rarely used at 100% capacity, that is with every possible sensor and creel holder in use. More often only a portion of the warp beam is used, a short warp is wound, or the yarns are widely spaced so some of the sensors are not used. In these cases the unused sensors must be individually disconnected, a job that takes again increases down time.